+Linux native asynchronous I/O. This engine also has a sub-option,
+\fBuserspace_reap\fR. To set it, use \fBioengine=libaio:userspace_reap\fR.
+Normally, with the libaio engine in use, fio will use the
+\fIio_getevents\fR\|(3) system call to reap newly returned events. With this
+flag turned on, the AIO ring will be read directly from user-space to reap
+events. The reaping mode is only enabled when polling for a minimum of \fB0\fR
+events (eg when \fBiodepth_batch_complete=0\fR).